U.S. patent number 4,280,949 [Application Number 06/011,681] was granted by the patent office on 1981-07-28 for modified polyester compositions containing mineral filler.
This patent grant is currently assigned to General Electric Company. Invention is credited to Ronald L. Dieck.
United States Patent |
4,280,949 |
Dieck |
July 28, 1981 |
Modified polyester compositions containing mineral filler
Abstract
Modified thermoplastic polyester compositions are provided which
comprise (a) a poly(1,4-butylene terephthalate) resin or polyester
copolymer and, optionally, a poly(ethylene terephthalate) resin,
(b) a modifier therefor comprising a combination of an acrylic or
methacrylic monomer grafted polymer of a conjugated diene alone or
combined with a vinyl aromatic and an aromatic polycarbonate, and
(c) a mineral filler selected from clay, mica and/or talc alone or
combined with glass fibers and, optionally, (d) a flame retardant.
Modifier (b) and mineral filler (c) provide enhanced resistance to
impact fracture, increased strength and improved resistance to heat
distortion in articles molded from the compositions.
Inventors: |
Dieck; Ronald L. (Evansville,
IN) |
Assignee: |
General Electric Company
(Pittsfield, MA)
|
Family
ID: |
21751521 |
Appl.
No.: |
06/011,681 |
Filed: |
February 12, 1979 |
Current U.S.
Class: |
524/445; 524/449;
524/451; 525/67 |
Current CPC
Class: |
C08K
3/34 (20130101); C08L 67/02 (20130101); C08L
67/02 (20130101); C08L 67/02 (20130101); C08L
51/04 (20130101); C08L 69/00 (20130101); C08K
3/34 (20130101); C08L 67/02 (20130101); C08L
67/02 (20130101); C08L 2666/02 (20130101) |
Current International
Class: |
C08K
3/00 (20060101); C08K 3/34 (20060101); C08L
67/00 (20060101); C08L 67/02 (20060101); C08L
069/00 (); C08L 067/02 () |
Field of
Search: |
;525/67
;260/4R,37PC |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Seccuro; Carman J.
Attorney, Agent or Firm: Morgan, Finnegan, Pine, Foley &
Lee
Claims
I claim:
1. A thermoplastic composition comprising:
(a) a polyester composition comprising:
(i) a poly(1,4-butylene terephthalate) resin;
(ii) a blend of a poly(1,4-butylene terephthalate) resin and a
poly(ethylene terephthalate) resin;
(iii) a block copolyester of poly(1,4-butylene terephthalate) and
an aromatic/aliphatic or aliphatic polyester;
(iv) a blend of (iii) and a poly(ethylene terephthalate) resin;
or
(v) a blend of (iii) and a poly(1,4-butylene terephthalate)
resin;
(b) an impact modifier therefor comprising a combination of:
(i) an acrylic or methacrylic monomer grafted polymer of a
conjugated diene alone or combined with a vinyl aromatic monomer;
and
(ii) an aromatic polycarbonate resin, in an amount of up to 60
parts per 100 parts by weight of (a) and (b) together; and
(c) an effective amount to improve impact strength after annealing
and at -20.degree. C. of mineral filler therefor selected from
clay, mica, talc or a mixture of any of the foregoing.
2. A composition as defined in claim 1 wherein the impact modifier
(b) is present in an amount of at least about 1.0 parts by weight
per 100 parts by weight of (a) and (b) together.
3. A composition as defined in claim 1 wherein the impact modifier
(b) is present in an amount of from about 2.5 to about 50 parts by
weight per 100 parts by weight of (a) and (b) together.
4. A composition as defined in claim 1 wherein the mineral filler
(c) comprises calcined kaolin clay.
5. A composition as defined in claim 4 wherein said clay filler is
a silane coupling agent surface-treated clay.
6. A composition as defined in claim 1 wherein said filler
component (c) is present in an amount of from about 1 to about 60
parts by weight per 100 parts by weight of (a), (b) and (c)
together.
7. A composition as defined in claim 1 wherein each said polyester
in component (a) has an intrinsic viscosity of at least about 0.4
deciliters/gram when measured in a solution in a 60:40 mixture of
phenol and tetrachloroethane at 30.degree. C.
8. A composition as defined in claim 7 wherein each said polyester
in component (a) has an intrinsic viscosity of at least about 0.6
deciliters per gram when measured in a solution in a 60:40 mixture
of phenol and tetrachloroethane at 30.degree. C.
9. A composition as defined in claim 1 wherein in components
(a)(i), (a)(ii) and (a)(v), said poly(1,4-butylene terephthalate)
resin is linear or branched.
10. A composition as defined in claim 9 wherein said branched
polyester is a high melt viscosity (1,4-butylene terephthalate)
resin which includes a small amount of a branching component
containing at least three ester forming groups.
11. A composition as defined in claim 1 wherein in said graft
copolymer resin component (b)(i), the conjugated diene polymer
comprises butadiene or isoprene, alone, or in combination with a
vinyl aromatic compound and the grafted monomer is a methacrylic
monomer.
12. A composition as defined in claim 11 wherein said graft
copolymer units of butadiene, styrene and a C.sub.1 -C.sub.6 alkyl
methacrylate.
13. A composition as defined in claim 12 wherein in said graft
copolymer the C.sub.1 -C.sub.6 alkyl methacrylate is methyl
methacrylate.
14. A composition as defined in claim 1 wherein said aromatic
polycarbonate resin includes units derived from bisphenol-A.
15. A composition as defined in claim 1 which also includes (d) a
flame-retardant amount of a flame-retarding agent.
Description
This invention relates to modified thermoplastic polyester
compositions which are moldable articles of improved impact
strength and thermal resistance. More particularly, the invention
pertains to compositions of (a) a poly(1,4-butylene terephthalate)
resin or a polyester copolymer resin and, optionally, a
poly(ethylene terephthalate) resin, which are modified with (b) an
effective amount of a resinous combination comprising an acrylic or
methacrylic monomer grafted polymer of a conjugated diene alone or
combined with a vinyl aromatic and an aromatic polycarbonate and
(c) a mineral filler alone or combined with glass fibers and,
optionally (d) a flame retardant.
BACKGROUND OF THE INVENTION
High molecular weight linear polyesters and copolyesters of glycols
and terephthalic or isophthalic acid have been available for a
number of years. These are described inter alia in Whinfield et al,
U.S. Pat. Nos. 2,465,319 and in Pengilly, 3,047,539, incorporated
herein by reference. These patents disclose that the polyesters are
particularly advantageous as film and fiber formers.
With the development of molecular weight control, the use of
nucleating agents and two-step molding cycles, poly (ethylene
terephthalate) has become an important constituent of injection
moldable compositions. Poly(1,4-butylene terephthalate), because of
its very rapid crystallization from the melt, is uniquely useful as
a component in such compositions. Workpieces molded from such
polyester resins, alone or combined with reinforcements, in
comparison with other thermoplastics, offer a high degree of
surface hardness and abrasion resistance, high gloss, and lower
surface friction.
Stable polyblends of poly(1,4-butylene terephthalate) and
poly(ethylene terephthalate) can be molded into useful unreinforced
and reinforced articles. See Fox and Wambach, U.S. Pat. No.
3,953,394, incorporated herein by reference.
Block copolyesters containing units derived from poly(1,4-butylene
terephthalate) and from an aromatic/aliphatic or aliphatic
polyesters are also known. See, copending application U.S. Ser. No.
752,325, filed Dec. 20, 1976, incorporated herein by reference.
Such block copolyesters are useful per se as molding resins and
also in intimate combination with poly(1,4-butylene terephthalate)
and/or poly(ethylene terephthalate.
It has been proposed to increase the impact strengths of polyesters
by adding various modifiers. For example, Brinkmann et al in U.S.
Pat. No. 3,591,659 disclose that a useful family of modifiers
comprises polyalkyl acrylates, methacrylates and/or ethacrylates.
Baron et al in U.S. Pat. No. 4,044,073 disclose that a useful
impact modifier for such polyesters is an aromatic polycarbonate.
Schlichting et al in U.S. Pat. No. 4,022,748 disclose that a
rubber-elastic graft copolymer having a glass temperature below
-20.degree. C. is a useful modifier. Lane, U.S. Pat. No. 4,034,013,
and Farnham et al, U.S. Pat. No. 4,096,202 disclose that useful
impact modifiers comprise multiple stage polymers having a rubbery
first stage and a hard final stage, preferably including units
derived from alkyl acrylates, especially butyl acrylates. Baron et
al in U.S. Pat. No. 4,034,016 (corres. German Pat. No. 2,650,870)
disclose an impact modifier combination comprising a blend of a
polyurethane and an aromatic polycarbonate. Copending application
Ser. No. 870,679, filed Jan. 19, 1978, discloses an impact modifier
combination comprising a segmented block copolyester and an
aromatic polycarbonate. Copending application Ser. No. 957,801,
filed Nov. 6, 1978, discloses an impact modifier combination
comprising a blend of a polyalkylacrylate and an aromatic
polycarbonate. Gergen et al, U.S. Pat. No. 4,090,996 disclose an
impact modifier combination comprising a selectively hydrogenated
monoalkenyl arene-diene block copolymer, and an engineering
thermoplastic, e.g., poly(aryl ether), poly(aryl sulfone),
polycarbonate, acetal, etc. Nakamura et al, U.S. Pat. No.
3,864,428, disclose poly(1,4-butylene terephthalate) or blends with
other polyesters, impact modified with conjugated diene-vinyl
copolymers grafted with methyl methacrylate and aromatic
polycarbonates, filled and/or flame retardant. Nakamura et al do
not disclose mineral fillers selected from clay, mica and/or talc.
All of the foregoing patents and the applications are incorporated
herein by reference.
It has now been discovered that such polyesters can be greatly
improved in impact strength as molded as well as after annealing
and at -20.degree. F., by intimately admixing therewith an impact
improving modifier combination comprising a conjugated
diene/acrylic or methacrylic monomer graft copolymer resin and an
aromatic polycarbonate resin and a mineral filler, selected from
clay, mica and/or talc. They can be produced more readily in a
variety of colors. As will also be shown, the new compositions of
this invention can also be rendered flame-retardant.
DESCRIPTION OF THE INVENTION
According to this invention, there are provided thermoplastic
compositions which are useful for molding, e.g., injection molding,
compression molding, transfer molding, and the like, the
compositions comprising:
(a) a polyester comprising:
(i) a poly(1,4-butylene terephthalate) resin;
(ii) a blend of a poly(1,4-butylene terephthalate) resin and a
poly(ethylene terephthalate) resin;
(iii) a block copolyester of poly(1,4-butylene terephthalate) and
an aromatic/aliphatic or aliphatic polyester;
(iv) a blend of (iii) and a poly(ethylene terephthalate) resin;
or
(v) a blend of (iii) and a poly(1,4-butylene terephthalate)
resin;
(b) an impact modifier therefor comprising a combination of:
(i) an acrylic or methacrylic monomer grafted copolymer of a
conjugated diene alone or combined with a vinyl aromatic monomer;
and
(ii) an aromatic polycarbonate resin, in an amount of up to 60
parts per 100 parts by weight of (a) and (b) together; and
(c) an effective amount of a mineral filler therefor selected from
clay, mica and/or talc, alone or in combination with reinforcing
fibrous glass.
The polyester resins (a) of the compositions of this invention are
available commercially or can be prepared by known techniques such
as by the alcoholysis of esters of terephthalic acid with ethylene
glycols with the free acids or with halide derivatives thereof, and
similar processes. These are described in U.S. Pat. Nos. 2,465,319,
and 3,047,359, and elsewhere. As has been mentioned, preparation of
the block copolyesters is described in Borman, Dolce and Kramer,
U.S. Ser. No. 752,325, filed Dec. 20, 1976, and incorporated herein
by reference.
Illustratively, the high molecular weight polyesters will have an
intrinsic viscosity of at least about 0.4 deciliters/gram and
preferably, at least 0.6 deciliters/grams as measured in a 60:40
phenol/tetrachloroethane mixture at 30.degree. C.
Especially useful when high melt strength is important are branched
high melt viscosity poly(1,4-butylene terephthalate) resins, which
include a small amount of e.g., up to 5 mole percent based on the
terephthalate units, of a branching component containing at least
three ester forming groups. The branching component can be one
which provides branching in the acid unit portion of the polyester,
or in the glycol unit portion, or it can be a hybrid. Illustrative
of such branching components are tri- or tetracarboxylic acids,
such as trimesic acid, pyromellitic acid, and lower alkyl esters
thereof, and the like, or preferably, polyols, and especially
preferably, tetrols, such as pentaerythritol, triols, such as
trimethylolpropane; or dihydroxy carboxylic acids and
hydroxydicarboxylic acids and derivatives, such as dimethyl
hydroxyterephthalate, and the like.
The branched poly(1,4-butylene terephthalate) resins and their
preparation are described in Borman, U.S. Pat. No. 3,953,404,
incorporated herein by reference.
Impact modifier (b) comprises a combination of (i) a resin of a
conjugated diene/vinyl copolymer grafted with acrylic or
methacrylic monomer and (ii) an aromatic polycarbonate. The block
copolymer resins (b)(i) can be made in known ways and they are
available commercially from Borg-Warner Corp. under the trade
designation BLENDEX, and from Kanegafuchi Chemical Industry Co.,
under the trade designation KANE-ACE. Any of the resins in U.S.
Pat. No. 3,864,428 can be used, especially those containing units
derived from butadiene or isoprene, alone or in further combination
with a vinyl aromatic compound. Especially preferably, graft
copolymer component (b)(i) will comprise a copolymer of styrene and
butadiene onto which has been grafted a C.sub.1 -C.sub.6 alkyl
methacrylate monomer, particularly methyl methacrylate. The
polycarbonate resins (b)(ii) can be made in known ways and they are
available commercially from sources, e.g., General Electric
Company, Pittsfield, Mass., U.S.A., under the trademark LEXAN. In
general, any of the aromatic polycarbonates described in Baron et
al, U.S. Pat. No. 4,034,016 can be used, especially those including
units derived from bisphenol-A.
The fillers will comprise mineral fillers, such as clay, mica
and/or talc and preferably clay, and especially that form of clay
known as calcined kaolin. It is also contemplated that the fillers
can be combined with reinforcing fillers, such as fibrous glass and
the like. The fillers can be untreated, but preferably, they will
be treated with silane or titanate coupling agents, etc. Especially
preferred is kaolin clay surface treated with a silane coupling
agent known as gamma aminopropyl triethoxysilane and sold by Union
Carbide Corp., under the trade designation A-1100 (GAP). The
coupling agent can be applied to the mineral filler by several
means. It can be tumble blended, or it can be deposited, e.g., from
solution in aqueous methanol.
The amount of the filler can vary widely depending on the
formulation and needs of the particular composition. Preferably,
however, the mineral filler will comprise from about 90%,
preferably from about 2 to about 40% by weight of filler (c) and
(a) and (b), combined. Especially preferably the filler will
comprise less than about 35% by weight of the combination.
It has further been found that even relatively minor amounts of the
modifier (b) are effective in providing significant improvements in
impact strength, and the like. In general, however, the modifier
(b) will be present in amounts of at least about 1% by weight,
preferably from about 2.5 to about 50% by weight of (a) and (b).
The ratio of graft copolymer to aromatic polycarbonate can vary
widely, i.e., within the range of 1 to 99 parts of the former to,
correspondingly, 99 to 1 parts of the latter, but in general, from
60 to 40 parts of the graft copolymer will be present for each 40
to 60 parts of the aromatic polycarbonate per 100 parts by weight
of (b).
The impact modified polyesters in combination with a filler can be
rendered flame retardant with an effective amount of a conventional
flame retardant agent (d). As is well known, flame retardants can
be based on elementary red phosphorus, phosphorus compounds,
halogen and nitrogen compounds alone or preferably in further
combination with synergists, such as antimony compounds. Especially
useful are polymeric and oligomeric flame retardant agents
comprising tetrabromobisphenol-A carbonate units; see, for example,
Wambach, U.S. Pat. No. 3,833,685, which is incorporated herein by
reference.
Other ingredients, such as dyes, pigments, drip retardants, and the
like can be added for their conventionally employed purposes.
The compositions of this invention can be prepared by a number of
procedures. In one way, the modifier and mineral filler or fire
retardants is put into an extrusion compounder with resinous
components to produce molding pellets. The modifier and mineral
filler and optional glass fibers are dispersed in a matrix of the
resin in the process. In another procedure, the modifier and
mineral filler and optional glass is mixed with the resins by dry
blending, then either fluxed on a mill and comminuted, or then are
extruded and chopped. The modifying agent and mineral filler and
optional glass can also be mixed with the resins and directly
molded, e.g., by injection or transfer molding techniques.
It is always important to thoroughly free all of the ingredients;
resin, modifier, mineral filler, and any optional, conventional
additives from as much water as possible.
In addition, compounding should be carried out to ensure that the
residence time in the machine is short; the temperature is
carefully controlled; the friction heat is utilized; and an
intimate blend between the resin, the modifier and the filler is
obtained.
Although it is not essential, best results are obtained if the
ingredients are pre-compounded, pelletized and then molded.
Pre-compounding can be carried out in conventional equipment. For
example, after carefully pre-drying the polyester and modifier and
the mineral filler, e.g., 4 hours at 250.degree. F., a single screw
vacuum vented extruder is fed with a dry blend of the ingredients,
the screw employed having a long transition section to ensure
proper melting. On the other hand, a twin screw extrusion machine,
e.g., a 53 mm Werner Pfleiderer machine can be fed with resin and
additives at the feed port and mineral down stream. In either case,
a generally suitable machine temperature will be about 450.degree.
to 560.degree. F.
The pre-compounded composition can be extruded and cut up into
molding compounds such as conventional granules, pellets, etc., by
standard techniques.
The composition can be molded in any equipment conventionally used
for glass-filled thermoplastic compositions, e.g., a Newbury type
injection molding machine with conventional cylinder temperatures,
e.g., 450.degree.-535.degree. F. and conventional mold
temperatures, e.g., 130.degree.-200.degree. F.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following examples illustrate the invention. They are set forth
as a further description but are not to be construed as limiting
the invention thereto. In the data tables, the abbreviation "N.D."
means not determined. All parts are by weight.
EXAMPLES 1 and 2
Dry blends of poly(1,4-butylene terephthalate) resin and/or
poly(ethylene terephthalate) (PET), methyl methacrylate grafted
butadiene/styrene copolymer, aromatic polycarbonate of bisphenol-A
and phosgene, mineral filler and mold release/stabilizer are
compounded and extruded at 520.degree. F. in an extruder. The
extrudate is pelletized and injection molded at 520.degree. F.
(mold temperature 150.degree. F.). The formulations and physical
properties are shown in Table 1.
TABLE 1 ______________________________________ Compositions
Comprising Polyester, Graft Copolymer, Aromatic Polycarbonate and
Clay Example 1 2 ______________________________________ Composition
(parts by weight) Poly(1,4-butylene tere- phthalate.sup.(a) (i)
39.5 24.5 Poly(ethylene terephthalate) -- 15.0 MMBS Graft
copolymer.sup. (b) (i) 15 15.0 Aromatic polycarbonate.sup. (b) (ii)
15 15.0 Santintone Clay.sup.(c) 30 30.0 Mold/release stabilizers
(to make 100%) Properties Distortion Temperature Under Load,
.degree. F. at 264 psi 178 175 Notched Izod impact, ft.lbs./in.
1/8" 1.58 1.34 Unnotched Izod impact, ft.lbs. 1/8" 37.6 31 Flexural
strength, psi 12,374 13,200 Flexural modulus, psi 500,600 486,400
Tensile strength, psi 7,488 7,226 Elongation, % 14.3 11.9
______________________________________ .sup.(a) (i) Valox 315,
General Electric Co., melt viscosity 72509000 poise. .sup.(b) (i)
KaneAce, B28 Kanegafuchi Chemical Industry Co., methacrylate
grafted butadiene/styrene copolymer. .sup.(b) (ii) LEXAN 105,
General Electric Co. .sup.(c) Englehard Co., New Jersey U.S.A.,
treated with 0.13% by weight o A1100,
gammaaminopropyltriethoxysilane coupling agent.
EXAMPLE 3
The procedure of Example 1 is used to prepare a flame retarded
composition of poly(1,4-butylene terephthalate), methacrylate
grafted butadiene-styrene copolymer, aromatic polycarbonate, clay
filler and flame retardants. The formulation and physical
properties are set forth in Table 2.
TABLE 2 ______________________________________ Composition
Comprising Polyester, Graft Copolymer, Aromatic Polycarbonate, Clay
and Flame Retardants. Example 3
______________________________________ Composition (parts by
weight) Poly(1,4-butylene terephthalate).sup.(a) (i) 36.8 MMBS
Graft copolymer.sup.(b) (i) 10 Aromatic polycarbonate.sup. (b) (ii)
10 Satintone clay.sup. (c) 30 Decabromodiphenyl ether 7 Antimony
oxide 6 Mold Release/stabilizer (to make 100) Properties Distortion
temperature under load, .degree. F. at 264 psi 177 Notched Izod
impact, ft.-lbs./in., 1/8" 7 Unnotched Izod impact, ft.-lbs./in.,
1/8" 12.0 Flexural strength, psi 14,400 Flexural modulus, psi
614,000 Tensile strength, psi 8250 Elongation, % 4.5
______________________________________ .sup.(a) (i); (b) (ii); (c)
See footnotes to Table 1 .sup.(b) (i) BLENDEX BTA111S from
BorgWarner Corp.
Obviously, other modifications and variations of the present
invention are possible in the light of the above teachings. For
example, the mineral filled compositions can be made with mica or
talc, and the poly(1,4-butylene terephthalate) and/or poly(ethylene
terephthalate) can be replaced with a copolyester. In addition,
part of the clay can be replaced with reinforcing fibrous glass. It
is therefore, to be understood that changes may be made in the
particular embodiments described above which are within the scope
of the invention as defined in the appended claims.
* * * * *